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| | [No title] (Site not responding. Last check: 2007-10-29) |
 | | When a mover sets a body in motion he implants into it a certain impetus, that is, a certain force enabling a body to move in the direction in which the mover starts it, be it upwards, downwards, sidewards, or in a circle. |
 | | Note that the implanted impetus is caused by a mover who imparts an initial velocity to a projectile; the impetus is proportional to the velocity: in fact, Buridan gave it a mathematical formulation: |
 | | Buridan used impetus theory to explain LINEAR as well as CIRCULAR motion, i.e., these were essentially the same; impetus was the force that tended to uphold the INITIAL motion, whether straight or circular; this idea survived for 300 years until Galileo. |
| www.physics.vanderbilt.edu /astrocourses/ast203/impetus_theory.html (650 words) |
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